Every car, by nature, has a degree of body flex whilst driving. This flexing causes the handling to be jittery on uneven surfaces and in intense driving situations. It is possible to reduce this significantly by fitting a strut brace in the engine bay. It is possible to get rear strut braces, but this guide deals with the more common front brace.
The brace I installed was an Apexi item, though most are very similar. BEWARE of US 240SX strut braces. The 240SX has a completely different engine and most brace clearances aren't suitable for the 200SX/Silvia.
You will need a 14mm socket, a set of Allen keys and a spirit level to fit the brace.
The most important thing about fitting a brace is to ensure that the car is on completely level ground. Uneven ground means uneven suspension struts and a body that has already slightly twisted. The result of this COULD be a twisted chassis over time. Use a spirit level to check the ground or drive.
The brace, as suggested, will be fitted on the two front suspension struts.
Undo the top strut nuts with a 14mm socket.
Place the brace over the strut bolts and hand tighten the nuts. Use the socket to tighten them evenly.
Once bolted to the struts, you will need to tighten the central brace to its mountings. Use an Allen key and a 14mm socket. These need to be TIGHT!
How easy was that? Before dropping the bonnet, just lower it carefully to ensure there is proper clearance. There should be, but do you know for sure?!